1. Field of the Invention
This invention relates to improvements in a tape cartridge, particularly used as an external memory such as a data cartridge for a computer, and to an assembly method of such a tape cartridge.
2. Description of the Prior Art
A data cartridge as shown in FIG. 9 is known in the art. The data cartridge 101 comprises a base plate 102 made of aluminum alloy and is provided with first and second hub installation shafts 103, 104 which vertically extend from the upper surface of the base plate 102. The base plate 102 is further provided with a drive roller installation shaft 105, first and second corner roller installation shafts 106, 107, a door installation shaft 108, tape guides 109, 110, and the likes which are all extended vertically from the upper surface of the base plate 102.
A hub 111 for supplying a magnetic tape 121 and a hub 112 for taking up the tape 121 are respectively rotatably mounted on the first and second hub installation shafts 103, 104. A drive roller 113 is rotatably mounted on the drive roller installation shaft 105. First and second corner rollers 114, 115 are rotatably mounted respectively on the corner roller installation shafts 106, 107. A drive belt 116 is passed around the drive roller 113 and the first and second corner rollers 114, 115 and is formed generally T-shaped. A door 118 is rotatably mounted on the door installation shaft 108 and biased in a direction to close under the action of a door spring 117. A mirror 119 is installed on the upper surface of the base plate 102. The cover 120 is made of a plastic and installed to the base plate 102 in a manner to cover the hubs 111, 112, the rollers 113, 114, 115 and the likes. The cover 120 is provided with a light protector 122 which is slidable relative to the cover 120.
As shown in FIG. 10, the cover 120 includes a cover main body 131. Temporary fixture pins 132, 132, 132, 132 are provided integrally with the cover main body 131. The cover main body 131 includes a rectangular upper plate 133. First, second, third and fourth side plates 134, 135, 136, 137 are formed integrally with the upper plate 133 and respectively generally along four sides of the rectangle of the upper plate 133, in which each side plate extends vertically from the lower surface of the upper plate 133. The temporary fixture pins 132 are located inside the side plates 134, 135, 136, 137 and extend from the lower surface of the upper plate 133. As shown in FIG. 11, each temporary fixture pin 134, 135, 136, 137 is formed at its tip end part with an engagement section 141 which is integral with a main body section 132A thereof.
The engagement section 141 includes a small diameter shaft section 142, and a large diameter shaft section 143 which is larger in outer diameter than the small diameter shaft section 142. The small diameter shaft section 142 is located between the large diameter shaft section 143 and the main body section 132A. A vertically extending slit 144 is formed throughout the small and large diameter sections 142, 143 in a manner to axially divide the engagement section 141 into two pieces, which are separate from each other so that the engagement section 141 can contract in outer diameter.
As shown in FIG. 12, when the engagement section 141 is inserted in the engagement hole 151 formed in the base plate 102, the small diameter shaft section 142 of the engagement section 141 is brought into engagement with the small diameter section 152 of the engagement hole 151, while the large diameter shaft section 143 of the engagement section 141 is brought into engagement with the large diameter section 153 of the engagement hole 151. As a result, the cover 120 is fixed provisionally on the base plate 102 in a state where the tip end faces 134a, 135a, 136a, 137a of the respective side plates 134, 135, 136, 137 of the cover 120 are in contact with the upper surface of the base plate 102.
Under such a state where the cover 120 is provisionally fixed to the base plate 102, small screws 161 are screwed so that the cover 120 is securely fixed to the base plate 102 thus completing the assembly of the data cartridge 101.
The assembly of the above data cartridge 101 is in general carried out in the order of the following steps:
(1) A step of supplying the base plate 102 which is provided with the hub installation shafts 103, 104, the drive roller installation shaft 105, the corner roller installation shafts 106, 107 and the likes.
(2) A step of assembling the mirror 119 to the base plate 102.
(3) A step of applying grease to portions of the base plate 102 with which portions the drive roller 113, the corner rollers 114, 115 and the likes are in contact.
(4) A step of installing the hubs 111, 112, the drive roller 113, and the corner rollers 114, 115 respectively to the hub installation shafts 103, 104, the drive roller installation shaft 105 and the corner roller installation shafts 106, 107, and of causing the drive belt 116 to be passed on the drive roller 113 and the corner rollers 114, 115.
(5) A step of winding the magnetic tape 21 on the hubs 111, 112 which have been assembled onto the base plate 102.
(6) A step of again applying grease to the portions of the base plate 102.
(7) A step of assembling the cover 120 to the base plate 102.
The above step is followed by a step of assembling the door 118 and the door spring 117 to the base plate 102, and a step of assembling the light protector 122 to the base plate 102.
Now, the steps (1) to (4) in the above steps (1) to (7) are carried out within a relatively short period of time; however, the step (5) of winding the magnetic tape 121 requires a relatively long time.
Accordingly, in case of assembling the data cartridge 101 upon continuously carrying out the steps (1) to (7), a long assembly time is unavoidably required owing to the long time is necessary in performing the step (5).
In order to solve the above problems, the following production method of the data cartridge has been developed and proposed: The steps of the above assembly method are divided into a former process including the steps (1) to (4) and a latter process of the steps (5) to (7). In the former process including the steps (1) to (4), many semi-completed (or-assembled) products of the data cartridge have been previously produced. In each semi-completed product, the hubs 111, 112, the drive roller 113, the corner rollers 114, 115, the drive belt 116 and the like are assembled to the base plate 102. These semi-completed products are transferred together with covers 120 to the latter process including the steps (5) to (7) at which operations such as winding the magnetic tape 121 are perform.
Now, in the above production method, each cover 120 is located by the base plate 102 of the semi-completed product provided with the hubs 111, 112, the drive roller 113 and the like, as a pair, and then transferred to the latter process including the steps (5) to (7). This causes the following problems to arise:
(a) Transferring is made in a state where the cover 120 is located by the base plate 102, and therefore a relatively large space is required.
(b) Dust and the like adhere to the hubs 111, 112, the drive roller 113, the drive belt 116 and the like on the base plate 102.
The above problems (a) and (b) can be solved as follows: The cover 120 is temporarily fixed to the base plate 102 with the temporary fixture pins 132 upon putting the cover 120 on the base plate 102. Thus, transferring is made in a state where the base plate 102 is covered with the cover 120. Then, the cover 120 is removed immediately before the latter process including the steps (5) to (7).
However, as shown in FIG. 12, the tip end faces 134a, 135a, 136a, 137a of the side plates 134, 135, 136, 137 of the cover 120 are brought into contact with the upper surface of the base plate 102 when the cover 120 is temporarily fixed to the base plate 102. This causes the following new problems to arise:
(c) There is the possibility of the grease applied onto the base plate 102 at the grease applying step (3) being adhered to the tip end faces 134a, 135a, 136a, 137a of the side plates 134, 135, 136, 137 of the cover 102 which has been temporarily fixed onto the base plate 102.
(d) When the cover 120 is again assembled to the base plate 102 after the magnetic tape 121 is wound on the hubs 111, 112 upon removing the cover 120 from the base plate 102, the grease adhered to the tip end faces 134a, 135a, 136a, 137a of the side plates 134, 135, 136, 137 of the cover 120 is in turn adhered to the magnetic tape 121 or the like thereby providing a source of trouble.